The invention relates to a signal generator for a mounting on holding tubes and, more particularly to a signal generator with a holding tube, having a base element for being placed on the holding tube and having a fastening element for fixing the base element on the holding tube.
Up to now, commercially available signal generators, for example, acoustic or visual signal generators, such as signal lights, buzzers or the like, have been provided with a base element which, for mounting on a holding tube, has a corresponding recess for it to fit onto the holding tube. For the firm fixing on the holding tube, a wedge-shaped clamping piece is laterally displaceable along the holding tube mounted in the base element. By way of a tension bolt accessible from the underside of the base element, this clamping piece is braced such that it is pressed, on the one side, against the base element and, on the other side, against the holding tube. This clamping results in a frictional engagement which causes the fixing of the base element on the holding tube.
On the one hand, such a base element requires relatively high expenditures and, if the tension bolt is not firmly tightened, leads to the risk of a loose holding.
Furthermore, for example, a multiple mounting armature is known from German Patent Document DE 295 12 658, which has a screw for the protection against torsion, by which the screwed connection is locked to a supporting tube. This requires the manufacturing of the necessary threads as well as the screwed connection of the supporting tube with the armature.
In contrast, it is an object of the invention to provide a signal generator having a holding tube and a fastening element, which can be produced at lower expenditures and ensures a secure fixing on the holding tube.
Based on a signal generator of the initially mentioned type, this object is achieved by a signal generator with a holding tube, having a base element for being placed on the holding tube and having a fastening element for fixing the base element on the holding tube. The fastening element cuts form-lockingly into the material of the holding tube and of the base element. The material of the fastening element, at least in its cutting-in area, is harder than the material of the holding tube. A recess, which, on the interior side, is open with respect to the holding tube, is provided for receiving the fastening element in the base, at least one sealing element existing for the watertight closure of the base element with respect to the holding tube.
Correspondingly, a signal generator according to the invention is characterized in that a fastening element is provided which cuts form-lockingly into the material of the holding tube and into the material of the base element. As a result of the cutting into the material during the mounting, neither the holding tube nor the base element need to have a special construction for establishing the form closure. As a result, the manufacturing expenditures are clearly reduced, in which case an extremely reliable fixing of the signal apparatus on the holding tube is ensured simultaneously.
For this purpose, the material of the fastening element is advantageously constructed to be at least partially constructed to be harder than the material of the holding tube and/or of the base element. This applies particularly in the areas of the fastening element which cut into the material, so that the cutting-in and thus the form-closure can be carried out particularly effectively.
In an advantageous further development of the invention, a recess, which, on the interior side, is bounded by the fitted-in holding tube and extends parallel to the holding tube, is provided in the base element for receiving the fastening element. In this manner, the fastening element and therefore also its areas cutting into the holding tube can extend along a certain length, so that, also when the penetration depth into the material of the holding tube or of the base element is low, a reliable holding is ensured.
In a particularly advantageous embodiment of the invention, the recess for receiving the fastening element is constructed to be accessible on the face side. As a result, the circumference-side outer wall of the base element remains unimpaired, whereby a better appearance of the base element and thus of the entire signal generator is achieved.
The recess for the fastening element is preferably constructed to be accessible from the upper face of the base element facing the signal generator. In this manner, the mounted fastening element, after the mounting of the signal generator, is arranged in the interior of the base element to be completely invisible from the outside.
In a particularly advantageous embodiment of the invention, a screw is provided as a fastening element whose thread diameter is at least partially larger than the clear measurement of the recess between the base element and the holding tube. When the screw is screwed in, which may, for example, be a conventional, commercially available sheet metal screw, the thread, on the one hand, therefore cuts into the holding tube and, on the other hand, into the base element. The manufacturing of the fastening element in this case requires no more expenditures because commercially available screws can be used. A corresponding recess must therefore be formed in the base. Since this recess can, in addition, be provided with a smooth wall, this embodiment requires minimal expenditures for fastening a signal generator.
The invention can be used in the case of holding tubes and base elements made of the most varied materials. Particularly the mounting on metallic or plastic tubes can be carried out without any problems. Likewise, the base element can consist of any material, for example, of a plastic material or of a metal.
In an advantageous embodiment of the invention, sealing elements are provided which seal off the area, in which the fastening element cuts into the holding tube, with respect to the remaining base element and thus with respect to the signal generator. This prevents an entering of water which can take place along the holding tube.
Furthermore, it is recommended to provide an insulation element in the base element by means of which a cable led to the signal generator in the holding tube is insulated with respect to a metallic holding tube. Such an insulation element can, for example, be constructed in the form of a connection piece immersed into the holding tube. In the area of this insulation element, the covering of a cable can therefore be removed without any problems, so that only the individual leads must be guided through the base element. This facilitates the handling during the electrical connection of the signal generator, in which case the individual leads are reliably insulated by the insulation element with respect to the holding tube.